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       <title>无标题文档</title>
       <style type="text/css">
          *{margin:0;padding:0;}
           .layer1{height:100px;}
            .layer1-1{width:50%; height:100px;  background:yellow;color:white;text-align:center;float:left;}
            .layer1-2{width:50%; height:100px;  background:blue;color:white;text-align:center;float:left;}
            .layer1-3{clear:both;}   
           .layer2{width:100%; height:200px;}         
                       .layer2-1{width:100%; height:100px; background:red;color:blue;text-align:center;text-align:center;}
             .layer2-1-1{width:30%; height:100px;  background:orange;color:white;text-align:center;float:left;}
            .layer2-1-2{width:30%; height:100px;  background:yellow;color:white;text-align:center;float:left;}
             .layer2-1-3{width:30%; height:100px;  background:red;color:white;text-align:center;float:left;}
            .layer2-1-4{clear:both;}
                     .layer2-2{width:100%; height:100px; background:blue;color:blue;text-align:center;text-align:center;}
                   .layer2-2-1{width:100%; height:50px; background:red;color:blue;text-align:center;text-align:center;}
                  .layer2-2-3{width:100%; height:50px; background:blue;color:blue;text-align:center;text-align:center;}


           .layer3{width:100%; height:130px;  background:green;color:white;text-align:center;}           
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    <body>
       <div class="layer1"><h1> </h1>
      <div class="layer1-1"><h1> </h1></div>
      <div class="layer1-2"><h1> </h1></div>
      <div class="layer1-3"><h1> </h1></div>> </div>
       <div class="layer2">   
<div class="layer2-1">
   <div class="layer2-1-1"></div> 
   <div class="layer2-1-2"></div> 
   <div class="layer2-1-3"></div>
   <div class="layer2-1-4"></div>

</div>      
<div class="layer2-2"> 
       <div class="layer2-2-1"></div>
          <div class="layer2-2-2"></div></div>
         <div class="layer3">底部</div>
    </body>
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